Brushless setup for E-Revo, advice please ?

[BrianG]

yes, 2X2s is 14.8v. However, if you go up to 6s, you can get smaller capacity batteries with no loss in runtime. The idea with higher voltage is to reduce current for a given power since high currents is what makes things heat up and run less efficiently.

For a given power, a 5Ah 6s pack will give very very close the same runtime as an 8Ah 4s pack.